1. Field of the Invention
The present invention relates to a cable-type steering device in which a steering wheel and a steering gear box are connected to each other by a flexible operating cable such as a Borden cable, and particularly to such a device with a variable steering gear ratio.
2. Discussion of Relevant Art
Conventional cable-type steering devices are known, for example, from Japanese Patent Application Laid-open Nos. 2000-25623, 10-59197 and 8-2431.
A driving pulley and a follower pulley in the conventional cable-type steering device are of the same columnar shape, and two operating cables are wound around grooves defined helically in outer peripheral surfaces of these pulleys. When a steering wheel is operated, one of the operating cables is wound around the driving pulley and drawn out of the follower pulley, and the other cable is drawn out of the driving pulley and wound around the follower pulley, whereby the rotation of the driving pulley is transmitted to the follower pulley.
Because the driving pulley and the follower pulley in the conventional cable-type steering device are of the same columnar shape, the steering gear ratio (a ratio of the steering angle of the steering wheel/a transmitted steering angle for wheels) is constant, irrespective of the position of the steering wheel. As a result, the steering characteristic cannot be made variable, e.g., from sensitive to obtuse, in accordance with the position of the steering wheel.